How Big will he get

[Moondoggie]

I train with backpack on some public trails near me, during my return I came across this young buck. I think he might be a good one when he grows up.

Any opinions on him?

IMO, public lands? Bang flop! Private with not a lot of pressure. Definitely would let him walk. I let two walk that were just outside the ears last year. Just didn't have the mass, nice tall tines though. Then achooser came in several times, but with only one side of his antlers. I kept thinking, I want the guy that knocked the antlers off.
Back to your deer. I think his antlers will grow taller, but only a couple inches wider. If you can get a pic after velvet, that's what I look at. The mass more than anything

 

[TxHeartShot]

I train with backpack on some public trails near me, during my return I came across this young buck. I think he might be a good one when he grows up.

Any opinions on him?

Shoot him and make some tamales.

 

[tsyarnall]

I watched this one until he was 5 1/2. Where I hunt there have been "stories" of giants getting taken out of season, so I didn't wait the one more year. He was about like your buck was when he was 3 1/2. With good nutrition and a little luck he might get to the size of mine. Mine was 166 6/8th and much more than I had ever dream of. Good luck

 

[victor3ranger]

Shoot big does, not small bucks.

Absolutely.
Hunting a true old doe is something we have done for several years now.
We try to pick ones that aren't breeding anymore. We call them muleheads, some are pretty impressive